90 



bill of a chick, is also present, as a chitinous knob on the doi'sal 

 surface, for the purpose of breaking the shell of the egg. The second 

 to the eleventh segments are each provided with a pair of lateral 

 stigmata. The thirteenth segment is provided posteriorly with two 

 strong spines, which are the principal organs of locomotion. The larva, 

 after leading a very active life for a short time, spins a cocoon about it 

 and passes into the pupa state. In this state of development the struc- 

 ture of the body corresponds to that of the adult insect, all the organs of 

 manducation and locomotion being present. After remaining in the 

 pupa state for about thirty days the insect emerges as the perfect imago. 



Having taken more time than I had originally intended in 

 describing the anatomy of these interesting parasites, a mere mention 

 of a few of the more common and chai'acteristic species must suffice. 



Fulex ( Sarcopsylla ) penetrans. — the Cliicoe or Jigger-^is found in 

 tropical countries. The female bores into the feet and ankles of men, 

 and many of the domestic animals, and, the abdomen being distended 

 as the ova undergo development, swells up to about the size of a pea, 

 causing often very severe inflammation. 



Ptdec irritans is the flea usually found in tilthy dwellings, the 

 larva being in the dust and dirt on and around the floors. It is 

 distinguished from others ordinarily met with by having no coli^- of 

 bristles ai-ound the neck. 



Pulex cnnis is found on dogs, cats., etc. It has a prominent collar 

 around its neck and a row of bristles along the under side of the head. 



Pulex fasciatus is found on the rat, mouse, etc. It has a row of 

 bristles around the neck, but none on the lower side of the head. 



Pulex (Typhlopsyllco) assimilis is found on the mole, shrew, etc., 

 and has been found by Mr. J. F, Whiteaves, of this city, on the chij)- 

 munk, Tamias striatus. The body is long and thin, the eyes are rudi- 

 mentary, and there is a row of eighteen bristles around the neck. 



